Re: [xmlvm-users] Collections Framework Design

[Arno P. <ar...@pu...>]

that sounds like a fascinating solution to an old problem! (although I 
have to admit I had to read your post twice to understand it :) )

Gergely: would you mind for the benefit of the people on the mailing 
list to post some code sniplet that shows the general approach? Kind of 
a distilled template to show how you do it? Probably easier than to go 
into your patch.

But I like your proposal and I would like to make that change. I think 
NSProxy might even help us with some other problems in XMLVM (@Wolfgang, 
Panayotis: overloading of UIView.drawRect). Nice idea!

Arno


On 3/26/10 10:58 AM, Gergely Kis wrote:
> Hi,
>
> There are already multiple patches in the review queue for the
> Collections Framework. Following my previous suggestion, I am now trying
> to open a discussion regarding the design of the collections framework.
> In our patch (http://xmlvm-reviews.appspot.com/18002) you can already
> see a partial implementation of this suggestion.
>
> Requirements:
> 1. Need to support seamless integration between regular ObjC types
> (NSArray ... etc.) and Java classes -> use categories
> 2. Need to support subclassing for non-final classes. This is a problem
> with using class clusters as the basis.
>
> The proposal:
> 1. Create the interfaces as protocols (java_util_List, java_util_Map ...
> etc.)
> 2. Implement the interfaces as categories of the non-mutable ObjC
> collection classes. (NSArray, NSSet, NSDictionary)
> - The mutator methods are implemented to throw
> UnsupportedOperationException. In essence you receive the same behavior
> as if you used Collections.unmodifiable*() methods
> 3. Only implement the mutator methods in the NSMutable* collection classes.
>
> At this point any ObjC collection can be used as a regular Java collection.
> Now we need to implement the actual concrete classes.
>
> However class clusters cannot be subclassed easily.
> The solution is to implement the concrete classes using NSProxy. (See
> how java_util_Vector is implemented in our patch).
> However, this implementation adds an unnecessary indirection and
> performance overhead. So the idea is to detect in the proxy class init
> function whether a subclass is instantiated.
> If it is not a subclass, then simply return the appropriate NSMutable*
> instance. Otherwise return the proxy.
>
> What do you think? If you agree with this approach we can clean up our
> implementation, and submit it separately.
>
> Best Regards,
> Gergely
>
> --
> Kis Gergely
> MattaKis Consulting
> Email: ger...@ma... <mailto:ger...@ma...>
> Web: http://www.mattakis.com
> Phone: +36 70 408 1723
> Fax: +36 27 998 622
>
>
>
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